There is a demand for estrogen-free contraception in order to reduce the risk of venous thromboembolism (VTE), particularly of obese women. A new long acting formulation of Levonorgestrel Butanoate (LB), delivered by injection, has been developed. Levonorgestrel (LNG) has a long history of clinical use in a variety of contraceptives (pills, intrauterine devices, and implants) and its efficacy and safety are well recognized. The CCTN will conduct a dose finding study of LB with doses selected on the basis of the results from the PK study, which is being conducted under a task order at Oregon Health and Science University. To obtain valid and reliable data to determine the duration of action, pharmacokinetics, indications of contraceptive efficacy, bleeding patterns, side effects, and safety of long-acting formulations of Levonorgestrel Butanoate (LB) for use as a contraceptive in obese and non-obese women of reproductive age. The objective of the dose- finding is to identify a dose that can provide reliable contraception for 4 months in non-obese and in obese women. To evaluate hormones as defined in the protocol for the dose finding study for Levonorgestrel Butanoate (LB), Measurement of hormones as defined in the protocol will contribute to evaluation of the effects of the long-acting injectable formulation of LB. This task order will be divided into two phases, phase 1 will be the base year (10 Months), including pharmacokinetic analysis and protocol development and to obtain IRB approval. Phase II will be for subject recruitment and enrollment.